The present invention relates to a thin film capacitor, a manufacturing method of the thin film capacitor, and an electronic component including the thin film capacitor.
An internal circuit of an electronic apparatus such as a computer or a portable terminal is provided with various surface mounting type electronic components. In recent years, to meet a demand for a higher performance and miniaturization of the electronic apparatus, further thinning of each electronic component (thinning of a film) has been an urgent need. Examples of such a thin film type electronic component include a thin film capacitor, a thin film inductor, a thin film LC composite component, a thin film concentrated constant device, a thin film distribution constant device, and a thin film laminate type composite component. Among them, examples of the composite component having the thin film capacitor include a low pass filter (LPF), a high pass filter (HPF), a band pass filter (BPF) which passes an only signal of a predetermined frequency range and decays a signal of a frequency range other than the predetermined frequency range, and a trap filter which removes the signal of the predetermined frequency range. Additionally, examples of an electronic component in which they are combined include a diplexer, a duplexer, an antenna switch module and an RF module.
Such a thin film capacitor usually has a constitution in which a lower electrode, a dielectric layer and an upper electrode are successively laminated on a base material made of an insulator. With the intentions of easily controlling a capacity and sufficiently securing a breakdown voltage (a dielectric breakdown limit value: hereinafter referred to as “the VBD”) between the electrodes, a conventional known thin film capacitor is provided with a resin layer (an insulating layer) which has an opening at a position facing the center of the dielectric layer on the electrode and which is disposed so as to cover a peripheral edge of the dielectric layer on the electrode. For example, Japanese Patent Application Laid-Open No. 2006-5293 discloses a thin film capacitor which has such an opening and is equipped with a diffusion preventive layer made of a metal or nitride between a dielectric layer and an upper electrode so as to prevent decrease of a VBD between the electrodes.
However, according to the investigation of the present inventor, it has been found that capacities easily fluctuate between the individual conventional thin film capacitors each provided with the resin layer having the opening. It has also been found that even in the above-mentioned conventional constitution equipped with the diffusion preventive layer, it is difficult to improve a VBD between the electrodes to a sufficiently satisfactory degree.